FET Input High Speed Light DetectorThis circuit is yet another design that converts current from a PIN photo diode to a voltage. It has a bandwidth that extends beyond 50MHz. . . Circuit by Dave Johnson P.E.-June, 2000

Form Push-Pull Driver using N-Ch & P-Ch Transistors This circuit can produce high speed output signals with fast rise and full times. The unique change pump action allows the voltage of the upper P-ch device to range from millivolts to hundreds of volts. The output current is only limited by the rating of . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000

High Impedance JFET BuffersI have used these circuits many times. They are great when you need a low gain AC signal amplifier with a very high input impedance. It is good to beyond 50MHz . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

High Speed Light Detector from FET InputThis circuit is yet another design that converts current from a PIN photo diode to a voltage. It has a bandwidth that extends beyond 50MHz . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

JFET High Impedance BuffersI have used these circuits many times. They are great when you need a low gain AC signal amplifier with a very high input impedance. It is good to beyond 50MHz. . . Circuit by David A. Johnson P.E.-July, 2006

FET audio mixer - This simple circuit mixes two or more channels into one channel (eg. stereo into mono) . The circuit can mix as many or as few channels as you like and consumes very little power. The mixer is shown with two inputs, but you can add as many as you want by just duplicating the "sections" which are clearly visible on the schematic. __ Designed by Aaron Cake

FET Input High Speed Light Detector - This circuit is yet another design that converts current from a PIN photo diode to a voltage. It has a bandwidth that extends beyond 50MHz. . . Circuit by Dave Johnson P.E.-June, 2000

FET Preamp Cable - This circuit comes from the Progressive Communications Receiver that is in most of the recent ARRL Handbooks and the article "A Progressive Communications Receiver", by Wes Hayward and John Lawson, QST, November 1981
1.

FET Preamplifier - Field Effect Transistor is an amplifying device in which the output current depends on the input voltage. The FET Pre Amplifier described here is a sensitive and stable Preamp circuit using an N-Channel FET and a PNP Bipolar transistor. This combination gives high input impedance and low output impedance with stabilized gain. __ Designed by D Mohankumar

Form Push-Pull Driver using N-Ch & P-Ch Transistors - This circuit can produce high speed output signals with fast rise and full times. The unique change pump action allows the voltage of the upper P-ch device to range from millivolts to hundreds of volts. The output current is only limited by the rating of . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000

Gate-Drive Method Extends Supply's Input Range - 26-Jun-03 EDN-Design Ideas Industrial and telecom applications often require a nonisolated, low-voltage supply from a high-voltage input. IC manufacturers have responded to that need with the application of high-voltage processes and offer control ICs that work to 50V and higher. That voltage is sometimes insufficient, and you need further design techniques to extend the input voltage __ Circuit Design by John Betten and Robert Kollman, Texas Instruments, Dallas, TX

Gate-drive transformer eases multi-output, isolated DC/DC-converter Designs - 04/12/13 EDN-Design Ideas Use this small transformer to produce four isolated outputs of about 1W each. Oftentimes the biggest obstacle in designing an isolated dc/dc converter is the transformer design, a prospect that sometimes discourages designers from undertaking an otherwise straightforward design task. You can take advantage of the characteristics of an off-the-shelf gate-drive transformer and produce four separate isolated dc outputs. Gate-drive transformers are actually ideal for low-power dc/dc power transfer, because they have already been optimized for a high product of voltage and time (ET, or volt-microsecond, product) as well as for low leakage inductance. __ Circuit Design by Robert Buono

H-BRIDGE Theory & Practice - A number of web sites talk about H-bridges, they are a topic of great discussion in robotics clubs and they are the bane of many robotics hobbyists. I periodically chime in on discussions about them, and while not an expert by a long shot I've built a few over the years. Further, they were one of my personal stumbling blocks when I was first getting into robotics[Chuck McManis] __ Designed by Chuck McManis

High Current MOSFET Flip Flop with Debounced Pushbutton - This circuit was adapted from the "Toggle Switch Debounced Pushbutton" by John Lundgren. It is useful where the load needs to be switched on from one location and switched off from another. Any number of momentary (N/O) switches or push buttons can be connected in parallel. The combination (10K, 10uF and diode) on the left side of the schematic insures the circuit powers up with the load turned off and the NPN transistor conducting. These components can be omitted if the initial power-on condition is not an issue. __ Designed by Bill Bowden

High Impedance JFET Buffers - I have used these circuits many times. They are great when you need a low gain AC signal amplifier with a very high input impedance. It is good to beyond 50MHz . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

High Speed Light Detector from FET Input - This circuit is yet another design that converts current from a PIN photo diode to a voltage. It has a bandwidth that extends beyond 50MHz . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

High-side driver feeds IGBTs & MOSFETs - 11/23/00 EDN-Design Ideas The low- to moderate-power system in Figure 1 provIdeas the interface between a pulse-width modulator and a high-side IGBT (insulated-gatebipolar-transistor) or MOSFET switch. You can use it to interface TTL or CMOS
circuitry to an H-bridge __ Circuit Design by Carlisle Dolland, Honeywell Engines and Systems, Torrance, CA

IC maintains uniform bias for GaAs MESFETs - 08/22/02 EDN-Design Ideas The gate-turn-on threshold voltage for GaAs MESFETs (gallium-arsenide metal-semiconductor field-effect transistors] varies considerably from part to part, even within a given lot. That behavior makes biasing difficult, especially if you want to design the device into a high-volume product. To overcome this drawback, you can introduce a current sensor that monitors the bias current and provIdeas __ Circuit Design by Ken Yang, Maxim Integrated Products, Sunnyvale, CA

Improve FET-based gain control - 12/06/01 EDN-Design Ideas One problemwith standard FET gain-control circuits is increased noise when you use the FET as a part of a resistive attenuator in series with an op amp. This configuration attenuates the signal before amplification; hence, it requires much higher gain bandwidth and better noise performance from the op amp __ Circuit Design by Ron Mancini, Texas Instruments, rmancini@ti/com

Improve On BIAS for GAAS FETs - 12/06/01 EDN-Design Ideas It's important to properly sequence the bias applied to an RF/microwave GaAs FET or a MMIC (monolithic-microwave-IC] amplifier. These devices are extremely sensitive to drain and gate voltage levels as well as to the order in which t __ Circuit Design by Tom Roberts, Anritsu Co, Morgan Hill, CA

Improved VBE Doubler - Circuit is a compensated Vbe doubler which operates over a wide current range. __ Designed by Jim Haggerman, Hagerman Technology LLC

Inverter 12 volt unit Mos-Fet Design - A Very Reliable, Efficient and Practical Design. Do Not ask how to Build this for Power ratings over 1000 watts, That is NOT Practical. __ Designed by G.L. Chemelec

Isolated MOSFET driver has wide duty-cycle range - 29-Apr-04 EDN-Design Ideas The main application for the circuit in Figure 1 is for driving power MOSFETs with signals ranging in frequency from 1 Hz to 300 kHz and with duty cycles from 0 to 100%. You achieve this goal by using a coreless pc-board transformer. The switching frequency in most power-electronics circuits ranges from a few hertz to a few hundred kilohertz __ Circuit Design by Jesus Doval-Gandoy and Moises Pereira Martinez, ETSI Industriales, Vigo, Spain

JFET High Impedance Buffers - I have used these circuits many times. They are great when you need a low gain AC signal amplifier with a very high input impedance. It is good to beyond 50MHz. . . Circuit by David A. Johnson P.E.-July, 2006

JFET-based DC/DC converter operates from 300-mV supply - 5/25/06 EDN-Design Ideas You use a JFET’s self-biasing characteristics to build a DC/DC converter that operates from power sources such as solar cells, thermopiles, and single-stage fuel cells, all of which deliver less than 600 mVYPDF has several circuits, you will need to scroll to find this one __ Circuit Design by Jim Williams, Linear Technology Corp, Milpitas, CA

JFETs offer LC oscillators with few components - 20-Jan-05 EDN-Design Ideas By using JFETs in unusual configurations, you can design simple, high-frequency LC oscillators with few passive components. The structure for implementing the amplifier stage comprises a JFET transistor that you configure as a common drain (Figure 1) . When the JFET transistor works in the saturation zone, the drain current, ID, is where IDSS is the maximum saturation current and VP is the __ Circuit Design by Herminio Martínez, Joan Domingo, Juan Gámiz, and Antoni Grau, Technical University of Catalonia, Barcelona, Spain

Low-Cost MOSFET Quashes Power Resistor - 06/09/94 EDN-Design Ideas At power-on, off-line power supplies use a resistor to provide start-up current for the PWM IC, current that is necessary to start driving the power switch. After a few periods, an auxiliary winding delivers a sufficient voltage to power the IC. Unfortunately, the start-up resistor dissipates heat and __ Circuit Design by Christophe Basso , European Synchrotron Radiation Facility, Grenoble, France